Add --disable-low-res-tiling. Disable low res tiling to save power.

cc/base/switches.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/base/switches.h"
 
 #include "base/command_line.h"
 
 namespace cc {
 namespace switches {
@@ skipping 27 matching lines @@
 
 // Allow heuristics to determine when a layer tile should be drawn with
 // the Skia GPU backend.  Only valid with GPU accelerated compositing +
 // impl-side painting.
 const char kEnableGPURasterization[] = "enable-gpu-rasterization";
 
 // Disable GPU rasterization, i.e. rasterize on the CPU only.
 // Overrides the kEnableGPURasterization flag.
 const char kDisableGPURasterization[] = "disable-gpu-rasterization";
 
+// When using CPU rasterizing generate low resolution tiling. Low res
+// tiles may be displayed during fast scrolls especially on slower devices.
+const char kEnableLowResTiling[] = "enable-low-res-tiling";
+
+// When using CPU rasterizing disable low resolution tiling. This uses
+// less power, particularly during animations, but more white may be seen
+// during fast scrolling especially on slower devices.
+const char kDisableLowResTiling[] = "disable-low-res-tiling";
+
 // The height of the movable top controls.
 const char kTopControlsHeight[] = "top-controls-height";
 
 // Percentage of the top controls need to be hidden before they will auto hide.
 const char kTopControlsHideThreshold[] = "top-controls-hide-threshold";
 
 // Percentage of the top controls need to be shown before they will auto show.
 const char kTopControlsShowThreshold[] = "top-controls-show-threshold";
 
 // Show metrics about overdraw in about:tracing recordings, such as the number
@@ skipping 111 matching lines @@
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   if (command_line.HasSwitch(switches::kDisableGPURasterization))
     return false;
   else if (command_line.HasSwitch(switches::kEnableGPURasterization))
     return true;
 
   return false;
 }
 
+bool IsLowResTilingEnabled() {
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(switches::kDisableLowResTiling))
+    return false;
+  else if (command_line.HasSwitch(switches::kEnableLowResTiling))
+    return true;
+
+  return true;
+}
+
 bool IsImplSidePaintingEnabled() {
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   if (command_line.HasSwitch(switches::kDisableImplSidePainting))
     return false;
   else if (command_line.HasSwitch(switches::kEnableImplSidePainting))
     return true;
 
 #if defined(OS_ANDROID)
   return true;
 #else
   return false;
 #endif
 }
 
 bool IsMapImageEnabled() {
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   if (command_line.HasSwitch(switches::kDisableMapImage))
     return false;
   else if (command_line.HasSwitch(switches::kEnableMapImage))
     return true;
 
   return false;
 }
 
 }  // namespace switches
 }  // namespace cc